Hamerton Zoo has been closed for the day after reports of a "serious incident" at the park.
Police and an air ambulance were called to the zoo near Huntingdon in Cambridgeshire, as visitors evacuated the site.
It is not yet clear what took place, however Cambridgeshire Constabulary confirmed the incident was not ongoing.
A spokesperson for the police force said: "We were called around 11.15 to reports of a serious incident at Hamerton Park.
"Officers attended the scene along with ambulance crews and MAGPAS [air ambulance].
"There is no further information at this time but we will provide an update when we are able to do so."
The spokesperson added: "There is nothing ongoing at the location now that would require anyone to be concerned."
On social media, there were unconfirmed reports that a tiger has escaped and that someone might have been bitten.
"Just been at Hamerton Zoo... One of the tigers escaped. Never run so fast in my life," Kevin Fernandez said on Facebook.
"They closed the zoo. Ambulance turned up. I think someone got bitten.
"We just saw everyone running out. The tiger bit and all the staff were shouting 'run get out'.
"We had to leave the zoo. A boy was missing and loads of ambulance turned up. Not quite sure what happened. One of the tigers got out though."
Victoria Holmes wrote on Facebook: "Well we've just had to hide thinking a tiger was loose. Something has gone wrong with a keeper and a tiger. Hope things are OK?"
A later Cambridgeshire Constabulary police statement confirmed that no animals had escaped from the zoo itself and said members of the public were safe, but did not rule out any injury to staff.
Hamerton Zoo is a 25-acre wildlife park which houses about 500 animals including Malaysian and White Bengal tigers.
More to follow.
This is a breaking news story and will be updated regularly as new information and developments become available.
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